1. Field of the Invention
The present invention relates to an electric control apparatus of a brake for controlling a brake hydraulic pressure of a vehicle (i.e. an automobile and a motorcycle), and more particularly to an electric control apparatus of a brake provided with both of an electric control system of a brake hydraulic pressure for controlling the brake hydraulic pressure electrically by means of an external hydraulic pressure source other than a master cylinder of the vehicle correspondingly to a quantity of an operation of the brake pedal of the vehicle and a mechanical control system of the brake hydraulic pressure as a fail-safe function for controlling the brake hydraulic pressure mechanically by means of the master cylinder independently from the electric control system.
2. Description of the Related Art
As conventional electric control apparatuses of a brake provided with both an electric control system of a brake hydraulic pressure and a mechanical control system of the brake hydraulic pressure as the fail-safe function of the electric control system, severally, the electric control apparatuses disclosed in Japanese Patent Publication No. 3,024,225, Japanese Laid-Open Patent Publication No. Hei. 10-147,224 and Japanese Laid-Open Patent Publication No. Hei. 11-341,604 can be cited.
Any of these conventional electric control apparatuses has an external hydraulic pressure supplying source including an accumulator storing a high hydraulic pressure as an essential component for the electric control system besides a master cylinder of the vehicle.
Because the conventional electric control apparatuses have the external hydraulic pressure supplying source including the accumulator as an essential component as described above, the conventional electric control apparatuses have the problems such that the configurations of the electric control system become complex and the numbers of the parts of the electric control apparatuses increase to make the increases of the costs of their production inevitable.
An object of the present invention is to provide an electric control apparatus of a brake simple in configuration and capable of constructing its electric control system of a brake hydraulic pressure without increasing the number of the parts thereof so much.
For the achievement of the foregoing object, an electric control apparatus of a brake according to a first aspect of the present invention comprises: a master cylinder for generating a brake hydraulic pressure according to an operation of a brake pedal; a first liquid passage for supplying the brake hydraulic pressure to a wheel cylinder by making the master cylinder and the wheel cylinder communicate with each other; a control device of the brake hydraulic pressure provided at a part of the first liquid passage, the control device including a control valve, a pump and a first reservoir containing a brake fluid as main components, the control device increasing and decreasing the brake hydraulic pressure to be supplied to the wheel cylinder by controlling operations of the components; detection means of a quantity of the operation of the brake pedal for detecting a physical quantity corresponding to the operation of the brake pedal; a second reservoir provided separately from the control device, the second reservoir storing the brake fluid in advance; a second liquid passage making the second reservoir communicate with the pump, constituting the control device, on a side of a suction opening of the pump, the second liquid passage being provided with a first on-off valve; a second on-off valve provided at a position in the first liquid passage, the position being nearer to the master cylinder than a position of the control device; and an electronic control unit for outputting a command signal for operating the control device, the electronic control unit including an electric control mode of the brake hydraulic pressure as an operation in a normal state of the unit and a mechanical control mode of the brake hydraulic pressure as an operation in an abnormal state in execution of the electric control mode, the electric control mode being for operating the pump with the first on-off valve being opened in order to supply a brake hydraulic pressure to the wheel cylinder, the brake hydraulic pressure being corresponding to a detection signal of the detection means in a state such that the second on-off valve is closed, the mechanical control mode being for supplying a brake hydraulic pressure to the wheel cylinder directly, the brake hydraulic pressure corresponding to the quantity of the operation of the brake pedal in a state such that the second on-off valve is opened after turning off components concerning the execution of the electric control mode.
According to the present aspect of the invention, an electric brake control system of a brake hydraulic pressure can be constructed that has a simple configuration and a not so much increased number of parts without the necessity of an external hydraulic pressure supplying source with an accumulator as an essential component.
That is, the aspect has the following features. The second reservoir, in which the brake fluid is previously stored, is provided separately from the control device. The second reservoir communicates with the pump on the side of the suction opening thereof, the pump being an original component of the control device, through the second liquid passage equipped with the first on-off valve. The second on-off valve is provided at a position in the first liquid passage, the position being nearer to the master cylinder than the position of the control device. Consequently, by such a configuration, in the electric control mode of the electric control unit, the pump operates with the first on-off valve being opened in order to supply a brake hydraulic pressure to the wheel cylinder. The brake hydraulic pressure corresponds to a detection signal of the detection means in the state such that the second on-off valve is closed. Therefore, because the present aspect is newly provided with only the second reservoir and uses the existing pump also as means for generating the brake hydraulic pressure in the electric control mode, the electric control system of a brake hydraulic pressure can be configured without increasing the number of the parts thereof so much, and with a simple configuration.
When an abnormality is generated in execution of the electric control mode, the electronic control unit of the aspect turns off the components concerning the execution of the electric control mode, namely the unit shifts to the mechanical control mode for supplying a brake hydraulic pressure, which corresponds to the quantity of an operation of the brake pedal in the state such that the second on-off valve is opened, to the wheel cylinder directly in place of the execution of the electric control mode. Thereby, the aspect can easily realize a fail-safe function.
Moreover, a second aspect of the present invention is an electric control apparatus of a brake according to the first aspect, wherein the second reservoir communicates with a part in the first liquid passage between the second on-off valve and the control device through a pressure relief valve by a third liquid passage.
According to the present aspect, if the brake hydraulic pressure generated by the pump becomes excessively high during the execution of the electric control mode, the aspect opens the pressure relief valve to return the brake fluid to the second reservoir through the third liquid passage automatically. Consequently, the safety of the aspect is further improved.
Moreover, a third aspect of the present invention is an electric control apparatus of a brake according to the first or the second aspect, the apparatus further comprising a brake simulator communicating with the master cylinder through a fourth liquid passage with a third on-off valve, wherein the electronic control unit is set to keep the third on-off valve in an opened state thereof when the unit shifts to the mechanical control mode in the case where an abnormality is generated in execution of the electric control mode after a beginning of an operation of the brake pedal in the electric control mode.
Because the master cylinder is provided with the brake simulator communicating with the master cylinder through the fourth liquid passage equipped with the third on-off valve in the present aspect, a driver does not feel unfitted feeling when the driver depresses the brake pedal. Furthermore, because the electronic control unit is set to keep the third on-off valve in the opened state thereof when the unit shifts to the mechanical control mode in the case where an abnormality is generated in the execution of the electric control mode after an operation of the brake pedal has begun in the electric control mode, the brake fluid fed to the brake simulator can effectively be utilized for execution of the mechanical control mode in place of the electric control mode. That is, the brake simulator can work also as an accumulator, which makes the electric control apparatus more effective.
Moreover, a fourth aspect of the present invention is an electric control apparatus of a brake according to any one of the first to the third aspects, the apparatus further comprising a brake light signal outputting part provided in the brake pedal, the brake light signal outputting part being connected with the electronic control unit to transmit a brake light signal to the unit when the brake pedal is operated, wherein the unit executes the electric control mode after confirming that the brake pedal has normally operated by the transmission of the brake light signal.
According to the present aspect, because the electronic control unit executes the electric control mode after the confirmation of the normal operation of the brake pedal by the transmission of the brake light signal, namely when the driver has normally depressed the brake pedal for braking, the aspect can correctly generate a braking force correspondingly to the brake operation of the driver. Consequently, the aspect can decrease the possibility of an erroneous action owing to the careless execution of the electronic control mode.
Incidentally, in the case where the electric control apparatus of a brake has an automatic braking mode for automatically braking a vehicle on a command signal from the electronic control unit even if the driver does not operate the bake with the brake pedal, the construction for the execution of the electric control mode based on the brake light signal is not applied to the electric control apparatus.
Moreover, a fifth aspect of the present invention is an electric control apparatus of a brake according to any one of the first to the third aspects, the apparatus further comprising a brake light signal outputting part provided on the brake pedal, the brake light signal outputting part being connected with the electronic control unit to transmit a brake light signal to the unit when the brake pedal is operated, wherein the detection means is connected with the electronic control unit to transmit the detection signal of said detection means to the electronic control unit when the brake pedal is operated, and the electronic control unit executes the mechanical control mode when either of both the signals is abnormal.
Thereby, the fail-safe function can further effectively be utilized.
Moreover, a sixth aspect of the present invention is an electric control apparatus of a brake according to any one of the first to the fifth aspect, wherein the control device includes an anti-lock braking system (ABS) function and a traction control system (ASR) function.
According to the present aspect, the electric control mode can be constructed by using the pump that is necessarily equipped by an existing control device of a brake hydraulic pressure having the ABS function and the ASR function. Moreover, the ABS function and the ASR function can be played as they are.